Technical Field of the Invention
This invention relates generally to computer networks and more particularly to dispersing error encoded data.
Description of Related Art
Computing devices are known to communicate data, process data, and/or store data. Such computing devices range from wireless smart phones, laptops, tablets, personal computers (PC), work stations, and video game devices, to data centers that support millions of web searches, stock trades, or on-line purchases every day. In general, a computing device includes a central processing unit (CPU), a memory system, user input/output interfaces, peripheral device interfaces, and an interconnecting bus structure.
As is further known, a computer may effectively extend its CPU by using “cloud computing” to perform one or more computing functions (e.g., a service, an application, an algorithm, an arithmetic logic function, etc.) on behalf of the computer. Further, for large services, applications, and/or functions, cloud computing may be performed by multiple cloud computing resources in a distributed manner to improve the response time for completion of the service, application, and/or function. For example, Hadoop is an open source software framework that supports distributed applications enabling application execution by thousands of computers.
In addition to cloud computing, a computer may use “cloud storage” as part of its memory system. As is known, cloud storage enables a user, via its computer, to store files, applications, etc. on an Internet storage system. The Internet storage system may include a RAID (redundant array of independent disks) system and/or a dispersed storage system that uses an error correction scheme to encode data for storage.
Distributed storage systems often utilize a three-phase process for writing consistently in a dispersed storage network (DSN) memory, where the three phases include: (1) A write phase; (2) A commit phase; and (3) A finalize phase. The three phases address consistency issues that may arise from different storage units of the DSN holding different revisions of encoded data slices, where data is dispersed storage error encoded to produce the encoded data slices. The three phases are known to utilize a threshold approach to advance the writing process to the next phase or to reverse the process when conflicts and errors arise to maintain consistency of revision storage.